Apparatus for manufacture of alkali-metal cyanid



F.1. METZGER.

APPARATUS FOIR MANUFACTURE 0F ALKALI METAL CYANID.

APPLICATION FILED DEC.5| 1918.

1,358,014, PatentedN0v.9,1920.

I jf I has encountered the 'notable obstac FLOYD J. METZGER, 0F NEWYORK, N. Y.,

ASSIGNOR TO AIR REDUCTION COMPANY,

INC., A CORPORATION OF NEW YORK.

Specification of Letters Patent.

Patented Nov. 9, 1920.,

Original application led March 16, 1918, Serial 110.222,812. Divided andthis application led lDecember 5, 1918.

To all 'Lc/wm t may 00H ocra:

yBe it known that l, FLOYD J. METZGER, a citizen of the United States,residing at New York city, inthe county of New York, State of New York,have invented certain new and useful Improvements in Ap aratus forlllanufacture of Alkali-Metal yanid; and l do hereby declare thefollowing to be a full, clear, and exact description of the invention,such as will enable others skilled in the art to which it appertains tomake and use the same. The present invention relates to the productionof alkali metal cyanids, and more particularly to an apparatus adaptedfor use in carrying out the method described in my co-pendingapplication Serial No. 222,812, filed March 16, 1918, of which thepresent application is a division.

The process referred to involves the treatment of mixtures 0f alkalimetal carbonates or alkali metal hydroxids (or both) together with coke,charcoal or equivalent carbonaceous material, and with or without theaddition of catalytic material such as iron, the operation beingconducted at an elevated temperature and in the presence of nitrogen ora nitrogencontaining gas.

'While the reactions involved in this general procedure are well known,various practical difficulties have been encountered in such endeavorsas have been heretofore made to introduce the process into commercialuse. For instance, in order to bring about the fixation of the nitrogenfor the production of cyanid in such processes, it is necessary, asabove indicated, to maintain a high temperature (approximately 850(3.40000 (j.) which, of itself, introduces complications in theconstruction and maintenance of the apparatus employed. So also, at thetemperature necessary for reaction, the alkali metal carbonate orhydroxid (or both), are in a molten or semi-uid condition, so that theentire 'furnace charge 1s more or less plastic, 1n which state itopposes `serious obstacles to the well-distributed contact between thenitrogen gas andthe fur`- nace charge, necessary for an efficient anduniform procedure. Y

l-lcretofore, the endeavor to realize an industrial utilization of thegeneral process e that Serial No. 265,388.

the semilplastic charge adheres, to a large extent, to the inner wallsof the furnace, in the absence of any` rovision for preventing suchadhesion. o meet this objection, it has been proposed, for example, tomaintain a protective layer of coke or other carbonaceous material (notcontaining alkali) -many of the proposals heretofore made, has

probably been due to the fact that during the operation the furnacecharge shrinks toa very great extent (the amount of shrinkarge, ofcourse, depending upon the nature and proportion o-f the ingredientsentering into the composition of the charge) and may amount to as muchas one`-third or more of its original volume. During this shrinking, thecontents of the furnace become channeled and this channeling allows thenitrogen gas to pass through'the furnace charge` with a correspondingdiminution of the desired contact, and with a resultant low andirregular yield of the alkali metal cyanld desired.

The present inventionprovides a mode of operation, which, in overcomingthedifiiculties hereinbefore referred to, supplies a satisfactorysolution of the industrial or commercial problem of producing 'alkalimetal cyanids from mixtures of the general character appropriate to thatmanufacture.

The accompanying drawing illustrates the preferred form of apparatusinvolved in the practice of the invention, the structure being shownpartly in side elevation and partly in section.

Referring to the drawing, 2 represents conventionally any suitableheating furnace, provided with a grate 3, fuel charging door 4. ash pitdoor 5, baliles G, and stack 7 The details of. -this furnace structuremay be chosento provide the desired heating effect,

and may be widely varied, as will be underf stood by those skilled inthe art.

Extending 'through the furnace is a cylinvdrical metal tube 1,preferablyE of an alloy containing essentially nickel, chromium and.

or without small vquantities of iron, with etc., 'the relativepropormanganese, silicon,

tions of the constituents of theV alloy being such that the tube willwithstand, to a satisfactory "degree,

y gases at the requiredcomparatively high 'i temperature.

The upper and lower ends of cost, .such as iron, so asto diminish theex- -ten feet for'l that may be of metal of less traverses theheatingside of the furnace,

ense of thestructure.

The metal tube or retort 1, isicarried on roller thrust bearings 8, onwhich it can be rotated, these bearings being suitably mounted toefficiently sustain the weight imposed upon them. The angularinclination of lthe tubular retort may be varied more or less inaccordance with the nature, both chemical and physical, of the mixturemaking up the charge,-a `suitable angle being, for instance the angleshown in the drawing. The upper end of the tubeml is provided with aconveyer an elbow pipe 12, whereby the retort can be y be desired. The

fedwith the. furnace charge automatically, and continuously orintermittently, as may. lower end of the tubular retort .is providedwith a gear 9 driven by the gear 10 from the driving shaft gear 11,

or the like, so as to rotate the tubular retort' at` the rate desired,suitable means- (not shown) being provided for varying the speed ofrotation.

rThe lower end of the tubular retort 1 is received Within a stationarycasing 14 closed at its upper end, suitable packing being provided, asshown at 15, to prevent the escape of gas at the joint betweenthestationary 'casing and the rotatable retort. A discharge screw thetreated charge received (from I 16 projects into the lower end of thetubular retort 1;,it is carried by a shaft 17 which passes through thecasing 14 and is driven from any suitable source of power by the bevelgears 18. The casing 14 is provided with a pending therefrom, and at thelower end'of the hopper is a discharge valve 2O by which the retort maybe discharged without permitting the escape of gasesfrom the casing andwithout admitting atmospheric air therethrough..

Y The nitrogen or nitrogen-containing gases are admitted to one end ofthe tubular retort and pass through the charde therein, and the reactiongases are allowed at the opposite end: Inthe drawing, a pipe the actionof the furnace and of a length of about 'ture passes through lin thewalls of the furnace,

13 discharging into f 'vtated continuously by means of the driving gearand, at the same time, the nitrogen or discharge hopper 19 de-A tolescape astenia for the inlet" ofv the nitrogen. or nitrogencontaining.gases is shown at 21, connected to endof the tubular retort,

' may be allowed to escape through the feeding devices for the charge,may be desired.v

ln the use of consisting of a suitable .mixture of alkali metalcarbonate? orv alkali metal .hydroxid (or both) and coke, charcoal, orother carbonaceous material, ywith or without a catalyst, such as iron,is fedI into the upper part of the tubular retort 1, which portion ofthe or. otherwise, as

retort constitutes a' preheating zone" for the.

charge. From the preheating zone, the mixand thence into the'coolingzone, that is to say, the'lower portion of the retort projecting beyondthe furnace wall. The chargeisinally withdrawn from the retort,

the apparatus, the charge,

the reaction zone Withwith the assistance of the discharge screw 16, anddrops into the hopper 19 from`whichit maybe removed, as desired, by thedischarge-valve 20.

rlhe operation is preferably va continuous one, the retort beingmaintained substantially lled with the charge 'throughout the operation,and the rate of discharge of the furnace charge being determined by. theoperation of the discharge'screw 16. rIhe ree tort, fwithvthe furnacecharge therein, is roadinitted to nitrogen-containing gases are Thenitrogen or nitrogen-containing gases Y pass up throughthe portion .ofthe charge in the cooling-zone, Land take up heat therefrom, so that thegases are preheated before they enter the reaction zone of the retort.So also, the temperature. of the treated charge is reduced by thecooling ei'ec't of the nitrogen or nitrogen-containing gases.

Within'thereaction Zone of the tubular retort, the charge is thoroughlyagitated by therotation of the retort, thereby efectually preventingcaking of the charge' and adherence thereof tothe walls of the retortand also preventing the formation of channels or fissures through thecharge'. Within this reaction zone, the charge, although reduced to apasty or semi-plastic condition, is thus `presented to the `bestadvantage to uniform and well distributed contact with the reac-V tiongases, so that a correspondingly high and regular yield of alkali metalcyanid re sults.

The upper end of the retort, constituting the preheating zone. beyondthev furnace walls, being more or less ille'd with the in- 'comingcharge, serves as a condenser for any volatile product or fume carried.along out of the reaction Zone, and the incoming charge is, at the sametime preheated byy means of the outgoing hot gases which pass throughit. l'

As the charge shrinks in the reaction zone of the retort, the shrinkageis continuouslyV and automatically taken care of by the supply of chargefrom the preheating zone, so that the reaction zone is kept completelyfilled. From the reaction zone, the treated charge,f-still in a plasticor semi-fluid condi-f' tion, enters continuously the cooling zone, andimmediately begins to solidify. ln so doing, the rotation of the tubularretort causes the material to become nodulizedinto lumpsor nodules ofrelatively small size, particularly appropriate to the subsequent usefor which the treated charge is especially intended, that is to say, asthe means for obtainingammonia by the passage of, steam therethrough orthe extraction of cyanidtherefrom. 'llhe-exit of the charge from thecooling zone`is assisted and regulated, as hereinbefore noted, by theconveyer screw 16, which may be opera/ted continuously orintermittently, as desired. i

It will be apparent that, instead of operati ing the entire processcontinuously, as preferred in most cases, the apparatus is likewise welladapted for operation intermittently, that is to sayby supplying 'itwith a given amount of furnace charge, treating and discharging the samein its entirety, and

f then supplying its place with a succeeding batch to be treated. Thenitrogenous gas, (whether nitrogen per se, or a gas or mixture of gasescontaining nitrogen) may be obtained from any desired and suitablesource as will be well understood by those skilled in the art.

Having thus described my invention, what I claim is:

l. An apparatus for the production of alkali metal cyanids by thetreatment of a mixture of an alkali and acarbonaceous'ma- :,terial, witha nitrogenous gas, comprising the combination of a tubular retortmounted at an incline to the horizontal, a furnace'inclosing a portionof the retort intermediate the ends thereof, said portion constitutingthe reaction zone of the retort, the lower portion of the retortextendingy beyond the furnace and providing a cooler noduli'zing zonefor the product, means for rotating ythe retort on its axis, feedingdevices for feeding the charge to the upper end of the retort, and aconduitcpmmunicating with the lower end of the retort` f or theintroduction of nitrogen gas.

2. An apparatus for the production of lalkali metal cyanids by thetreatment of a mixture of an alkali and a carbonaceous ma- -terial witha nitrogenous gas, comprising the combination of a tubular retortmounted at anincline to the horizontal, afurnace'vin-y closing a portionof the retort intermediate the ends thereof, means for .rotating the retort on its axis, feeding devices for feeding the charge to the upperendx of the retort,

means for assisting the discharge of thev treated 'material from thelower end' of the retort, and a conduitl communicating with one enc'l ofthe retort for the introduction of the nitrogenous gas; substantiallyasl (described. v v

3. An apparatus for the production of alkali metal cyanids by thetreatment of a mixture of an alkali and a carbonaceous material with anitrogenous gas, comprising the combination of a tubular retort'mountedf at an incline to the horizontal, a furnace inclosing a portion of theretort intermediate the ends thereof, means for rotatlng the retort onits axis, feeding devices for feeding the combination of .a tubularretort mounted at an incline to the horizontal, a furnace inclosing aportion of the retort intermediate jthe ends thereof, s'aidv portionconstituting the reaction zone of the retort, means for the charge tothe upper end of the retort, y

ion

rotating the retort Eon its axis, feeding devices for feeding the chargeto the upper end of the retort, a closed casing spaced from the furnaceand connected to the reaction zone by a portion of the retort whichprovides a cooling zone, and a lconduit connected with the casing forthe introduction of the nitrogenous gas; substantially as described.

5. Anapparatus for thel production of alkali metal cyanids by thetreatment of a mixture of an alkali metal compound and a carbonaceousmaterial with a notrogenous gas, comprising the combination of/aninclined tubular retort, a furnace `inclosing a Y.

portion of theretort intermediatey its ends, means for rot'atingtheretort about its axis, means for feeding the chargeto the upper 'end ofthe retort, means for assisting the discharge of the treated materialfrom the lower end of the retort and means for introducing nitrogenousgas to the retort.

In testimony whereof l aiiix my signature,

` FLOYD J. METZGER

